WM8946ECSSLASHR datasheet(35/175 Pages) WOLFSON

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Production Data

WM8946

PD, July 2012, Rev 4.3

3D SURROUND

The 3D-stereo surround effect is part of the SE1 block. This function uses time delays and controlled

cross-talk mechanisms to adjust the depth or width of the stereo audio. The 3D-stereo surround effect

includes programmable high-pass or low-pass filtering to limit the 3D effect to specific frequency

bands if required. The structure of the 3D surround processing is illustrated in Figure 15.

HPF

LPF

bypass

HPF

LPF

bypass

z-n

forward_l

forward_r

cross_r

cross_l

Figure 15 3D Surround Processing

The 3D surround depth is programmable; the default setting is OFF. The 3D surround processing can

also be configured to create a mono mix of the Left and Right channels.

The 3D effect is enabled on the left and right channels using the SE1_3D_L_ENA and

SE1_3D_R_ENA register bits defined in Table 13. These bits can be set independently of each other.

For the derivation of the other associated registers, refer to the configuration tools supplied with the

WM8946 Evaluation Kit.

5-NOTCH FILTER

The 5-notch filter is part of the SE1 block. This function allows up to 5 programmable frequency

bands to be attenuated. The frequency and width of each notch is configurable; the depth of the

attenuation may also be adjusted. The default setting is bypass (OFF).

The notch filters may be enabled on the left and right channels using the SE1_NOTCH_L_ENA and

SE1_NOTCH_R_ENA register bits defined in Table 13. Note that, although the 5-notch filter can be

enabled on the left/right channels independently, the parameters that define the notch filters apply

equally to the left and right channels, when enabled.

The notch filter coefficients are programmed in registers R72 to R91. For the derivation of these

registers, refer to the configuration tools supplied with the WM8946 Evaluation Kit.

Note that the notch filters should not be configured for centre-frequencies below 120Hz. To apply

filtering at low frequencies, the SE1 High Pass Filter should be used.

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